Is it OK to store additional objects in an Exception? - grails

Question

I needed to display some validation messages received from the service each in its proper place, and I solved it putting the messages in an exception:
class InvalidInputException extends RuntimeException {
def errors
InvalidInputException(String s) {
super(s)
}
InvalidInputException(String s, errors) {
super(s)
this.errors = errors
}
}
That way, I could throw the exception sending the errors:
if (errors) {
throw new InvalidInputException("There were some errors", errors)
}
.. and then I deal with the errors later in the controller, after catching the exception:
...
catch (InvalidInputException e) {
if (e.errors) {
// set them up to display appropriately
}
// render the view
}
Now, I've read somewhere that Groovy's exceptions can cost too much, so... is this too bad?
What problems may I encounter putting additional data in an Exception?
It's much easier than fiddling with returned error messages, and the code is much shorter.

Answer 1

If you are concerned about the performance of exceptions in Java, I suggest you to look at this other question.
If you not create a exception, the other possibility is to make your service return an object that represents the result of this flow. Something like:
class MyServiceResult {
List<String> errorCodes = [] //codes for i18n
void addErrorCode(String errorCode) {
errorCodes << errorCode //add error to list
}
boolean isValid() {
return (!(errorCodes.size() > 0)) //if we have errors then isn't valid.
}
List<String> getErrorCodes() {
return errorCodes.asImmutable()
}
}
And just use it in your service method
class MyService {
MyServiceResult someMethod() {
MyServiceResult result = new MyServiceResult()
...
result.addErrorCode('some.key.here')
...
return result
}
}
class MyController {
def myService
def action() {
MyServiceResult result = myService.someMethod()
if(!result.isValid()) {
//handle errors
}
}
}
But it's important to say that it can be 2x slower than creating an exception. You can check all details in this post.